BERLIN, MD, USA
N56094
Piper PA-28R-200
On the third flight of the day, the engine started without difficulty and no anomalies observed. The pilot taxied onto the runway, advanced the throttle, and executed a normal takeoff. The airplane climbed to a cruise altitude of approximately 2,000 feet msl. After reaching 2,000 feet, the engine started running rough, and the airplane started to descend. The pilot attempted a forced landing to a road, but struck wires while maneuvering to avoid a construction vehicle. The number 3-cylinder exhaust valve stem was found fractured into two pieces, and evidence of a fatigue crack on the fracture surface was identified. The engine was remanufacture to zero time on October 10, 1979, and then installed on January 10, 1981. At the time of the accident, the engine had approximately 1,325 hours of operation and 20 years since overhaul. A service instruction published by the engine manufacture recommends that the engine be overhauled every 2,000 hours or 12 years which ever comes first.
On October 8, 1999, at 1623 eastern daylight time, a Piper PA-28R-200, N56094, was substantially damage during a forced landing near Berlin, Maryland. The certificated private pilot and passenger received serious injuries. Visual meteorological conditions prevailed for the personal flight that originated from Ocean City Municipal Airport, Ocean City, Maryland, about 1604. No flight plan was filed, and the flight was conducted under 14 CFR Part 91. According to the pilot, an annual inspection was completed on the airplane the day before the accident. On that same day the annual was completed, the pilot conducted an instrument training flight with a flight instructor. The instructor observed the preflight, and no anomalies were noted. Both the pilot and instructor boarded the airplane, and the engine started on the first attempt. The training flight was completed with no mechanical problems being observed. On the day of the accident, the pilot used a cellular phone to get a weather briefing while driving to the airport. The weather was good, and he did not anticipate any problems for the flight to Ronald Reagan Washington National Airport, Washington, District of Columbia. A preflight was completed, and the pilot boarded the airplane. He organized the cockpit, pulled out the checklist, and started the engine on the first attempt. The run-up checks were completed, and a normal takeoff was executed via runway 5. Once airborne, the pilot selected the gear up, but it did not retract. After placing the gear handle in the down position, and having the tower confirm that the landing gear was down, the pilot executed a normal traffic pattern, and landed without incident. The maintenance chief at the facility that completed the annual adjusted the emergency gear handle, and the gear was swung approximately 3 times. The pilot accepted the airplane, taxied to runway 5, and departed for Washington National. Once at 5,500 feet, the pilot configured the airplane for cruise flight, and noted that the indicated airspeed was 135 mph. He added that before the annual, the airplane would indicate 130 mph for the same flight conditions. The flight was completed, and the pilot went inside to meet a friend. After a short discussion, the two decided to fly to Ocean City for lunch, and then return. They walked out to the airplane, and the pilot conducted a "quick" preflight. They both boarded, and the pilot started the engine on the first attempt. He then taxied to runway 15, executed a normal takeoff, and climbed to a cruise altitude of 2,500 feet msl. The flight was completed, and nothing abnormal was observed. While at Ocean City, the airplane received a full load of fuel. The pilot's memory of the accident flight was limited, but he did remember departing Ocean City, experiencing a loss in power, and hearing a clicking sound, but nothing else. According to the passenger, the pilot paid for the fuel at Ocean City then walked over to the airplane. They both boarded, and the pilot began using a checklist. The engine started without any difficulty, and no anomalies were observed during the run-up checks. The pilot then taxied the airplane onto the runway, advanced the throttle, and executed a normal takeoff. After becoming airborne, the pilot placed the airplane in a climb attitude until reaching a cruise altitude of approximately 2,000 feet msl. Approximately 6 miles from Ocean City, the pilot contacted air traffic control (ATC), and requested clearance through restricted airspace. While ATC was responding to the pilot's request, the engine started running rough. The pilot switched tanks, turned on the boost pump, and adjusted the throttle plus the mixture, but the engine continued to run rough. While descending at 250 to 500 feet per minute, the pilot made a mayday call, and started looking for a place to land. He identified a new road that was under construction, and maneuvered the airplane to a downwind, base, and then final. On final, the pilot and passenger identified a construction vehicle enter the road. They realized there was insufficient space to land, so the pilot decided to adjust his touchdown point. He traded airspeed for altitude, and started a turn to the right. The airplane then contacted wires, and the stall horn sounded. The airplane came to rest on top of a bobcat that was setting on a trailer attached to a parked pickup truck. According to a Federal Aviation Administration Inspector, witnesses at Bunting's Field Airport, Berlin, Maryland, saw and heard the airplane fly over. They noticed that the engine was not operating normally and thought the pilot was going to land on the 3,000-foot grass strip at their location. According to the facility that fueled the airplane at Ocean City, a visual inspection of the fuel at their location was preformed after the accident, and no contaminates were identified. In addition, no other aircraft fueled on the day of the accident reported any problems with contaminated fuel. On December 16 and 17, 1999, an engine teardown was conducted in Williamsport, Pennsylvania, under the supervision of the Safety Board Investigator. During the examination, the fuel servo was tested and all of the engine accessories were examined. No pre-impact failures were identified with any of these components. The crankshaft was rotated and compression was obtained on the number 1 and number 4 cylinders, but not on the number 2 and number 3 cylinders. Examination of the number 2 cylinder revealed impact damage to the intake valve. Examination of the number 3 cylinder showed that the exhaust valve stem had separated, and the head of the valve was imbedded in the cylinder. In addition, the fracture surface on the portion of the valve stem that was still attached to the head had multiple impact marks on it. Examination of the engine logbook revealed that the engine was remanufacture to zero time on October 10, 1979, and then re-installed on January 10, 1981. At the time of the accident, the engine had approximately 1,325 hours of operation since overhaul. In addition, on October 7, 1999, an annual was completed. A review of the billing invoice for the annual revealed a compression check was done for all four cylinders, and that the results were recorded. The number 1 cylinder produced 72/80 PSI, the number 2 cylinder produced 73/80 PSI, the number 3 cylinder produced 70/80 PSI, and the number 4 cylinder produced 74/80 PSI. According to a "Service Instruction" titled "Recommended Time Between Overhaul Periods" published by the engine manufacture. The engine should be overhauled every 2,000 hours. In addition, the publication states that, "...all engines that do not accumulate the hourly period of time between overhauls specified in this publication are recommended to be overhauled in the twelfth year." According to a Safety Board Material Laboratory Factual Report, "the fracture face on the valve was covered with heavy accumulations of combustion deposits and oxides. No evidence of necking deformation was noted adjacent to the fracture. "...undamaged areas of the fracture contained ratchet marks and crack arrest positions indicative of fatigue cracking."
The failure of the number 3-cylinder exhaust valve stem due to fatigue cracking.
Source: NTSB Aviation Accident Database
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